That's an immense amount of responsibility and productivity for one person. Gates may seem relatively relaxed, but like the rest of us mere mortals, he also feels anxious at work sometimes.

On Tuesday, during an interview at Hunter College in New York City, a student asked Gates about his worries and weaknesses at work.

"[When I'm] dealing with hiring issues and management issues ... I always had to get other people to come in and help out who have a deep sensitivity as to how we were going to build up the team," Gates said. "Even areas like sales and accounting — the work that wasn't exciting to me as the engineering pieces. If I'm not excited about something, I'm probably not going to be as good at it."

Gates added that communicating with government makes him anxious, too. In his latest letter discussing the Gates Foundation's charity work, he wrote that President Trump's "America First worldview" has made his team's foreign aid projects more difficult. In March 2017, Gates visited Trump at the White House to have a conversation about the proposed budget cuts to the State Department and the US Agency for International Development.

"Also governmental relations," Gates said. "I didn't realize until too late how important those were."

It's a reminder that work-related anxiety is part of the human experience. And no one is immune to it— not even Bill Gates.